The Green Lantern

Green My Blog

What’s the best way to make a Web site energy-efficient?

I have a blog. It’s just something for my friends and families, but I imagine it still sucks up a lot of energy. After all, Web sites have to bounce around servers and computers all over the place. I’ve seen some blogs with tickers to calculate their carbon footprint.  Should I be concerned about mine?

Given all the equipment it takes to run the Internet and how quickly it is growing, it sure seems as if the Web would have an enormous environmental impact. Indeed, some folks now estimate that information technology accounts for a larger carbon footprint than that bugaboo of global-warming scolds everywhere, the airline industry. According to a recent government report (PDF), data centers—the rooms full of servers and network equipment that power the Web—account for about 1.5 percent of U.S. electricity usage per year. Journalist Nicholas Carr even suggested that the average Second Life avatar consumed as much energy as the average Brazilian.

But the Lantern believes these stats exaggerate the contribution of the Internet to global warming. At the peak of the Internet boom, some warned that the growing network would produce an untenable demand for electricity. Those claims—including the notion that an old-school Palm Pilot used as much electricity as a refrigerator, just to access its wireless network—have been rather thoroughly debunked. Moreover, it takes far less energy to transmit data than it does to move atoms. In other words, downloading an MP3 takes less energy than buying a CD, posting a book online allows readers to use less resources than printing a physical copy, and watching a conference online emits less carbon than attending in person. (For the Lantern’s earlier take on reading newspapers online, click here.) Meanwhile, computers and computing equipment are getting substantially more energy-efficient every year.

The environmental impact of accessing a single article or song may have gone down, but people are now getting many, many more pieces of information. After all, most of today’s bloggers weren’t posting their thoughts on cafe bulletin boards 15 years ago. Even if it’s more energy-efficient to post or download data online, that advantage could be overwhelmed by the massive amounts of new information.

Jonathan Koomey, the energy researcher who challenged the Palm Pilot theory, has now estimated how much energy it takes for one gigabyte of data to travel over the Internet. Along with another consultant named Cody Taylor, Koomey added up the electricity needed to run the servers hosting the data, the Internet backbone over which those data travel, and the network connections through which the data flow. (Their numbers don’t include the energy used by end-user equipment—like home computers and wireless routers.) In total, they estimate that in 2006, it took, on average, between nine and 16 kWh of electricity to transmit a gigabyte of data. (Koomey and Taylor’s research—published here [PDF]—was sponsored by an online-advertising firm.)

What does that mean for your personal blog? In terms of direct pollution, the impact is likely to be pretty small. To provide a reference point, the popular blogging site WordPress said it transferred about 161,100 gigabytes of data last year across 3,132,606 active blogs. Do the math, and that adds up to only about 51 megabytes of data transferred per blog per year—a tiny amount. Of course, a given blogger’s bandwidth will be much higher if he or she receives lots of traffic or posts large images and videos. But even those whose sites transfer a couple of gigabytes a month would be responsible for just a few hundred kilowatt-hours of electricity per year. Using somewhat outdated stats from the Department of Energy, that would put even one of those larger blogs somewhere in the range of the average household’s microwave.

What kind of environmental impact does Slate have? Compared with a personal blog, ourcarbon footprint is pretty hefty. Slate’saverage daily bandwidth is somewhere around 280 gigabytes. Using Koomey and Taylor’s 2006 numbers—which are simply Internet-wide averages—that would mean Slate’s traffic is responsible for somewhere between 650 and 1,700 tons of CO2-equivalent per year. (That would be equivalent to the footprint of perhaps 50 Americans or one Material Girl.)

If the carbon footprint of your blog keeps you up at night, it’s possible to make a few changes for the better. Koomey and Taylor estimate that cooling and ventilating servers accounts for about half of the energy needed to power the Internet, and a whole range of “green” hosting services has sprouted up to mitigate the carbon impact of these operations. (Many of them buy renewable-energy certificates, as opposed to cutting down on energy use in the first place.)  CO2Stats, a startup that estimates a site’s carbon footprint for a fee, advises developers on how better to encode their sites for more efficient data transfers. But even on your own, you can make simple changes like posting fewer or less bulky pictures, cutting down on the electricity needed to access your musings.

Of course, none of this takes into account the energy required to power those computers used by your faithful following to read and comment on your blog. If your readers use desktop machines with CRT monitors and other electricity-hogging accessories, they may offer the best hope of reducing carbon emissions—something worth mentioning on your blog.

Is there an environmental quandary that’s been keeping you up at night? Send it to, and check this space every Tuesday.